/* * Copyright (C) 2011-12 Synopsys, Inc. (www.synopsys.com) * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * */ #include #include #include #include #include #include "../../drivers/irqchip/irqchip.h" #include #include #include /* * Early Hardware specific Interrupt setup * -Called very early (start_kernel -> setup_arch -> setup_processor) * -Platform Independent (must for any ARC700) * -Needed for each CPU (hence not foldable into init_IRQ) * * what it does ? * -setup Vector Table Base Reg - in case Linux not linked at 0x8000_0000 * -Disable all IRQs (on CPU side) * -Optionally, setup the High priority Interrupts as Level 2 IRQs */ void __cpuinit arc_init_IRQ(void) { int level_mask = 0; /* Disable all IRQs: enable them as devices request */ write_aux_reg(AUX_IENABLE, 0); /* setup any high priority Interrupts (Level2 in ARCompact jargon) */ level_mask |= IS_ENABLED(CONFIG_ARC_IRQ3_LV2) << 3; level_mask |= IS_ENABLED(CONFIG_ARC_IRQ5_LV2) << 5; level_mask |= IS_ENABLED(CONFIG_ARC_IRQ6_LV2) << 6; if (level_mask) { pr_info("Level-2 interrupts bitset %x\n", level_mask); write_aux_reg(AUX_IRQ_LEV, level_mask); } } /* * ARC700 core includes a simple on-chip intc supporting * -per IRQ enable/disable * -2 levels of interrupts (high/low) * -all interrupts being level triggered * * To reduce platform code, we assume all IRQs directly hooked-up into intc. * Platforms with external intc, hence cascaded IRQs, are free to over-ride * below, per IRQ. */ static void arc_mask_irq(struct irq_data *data) { arch_mask_irq(data->irq); } static void arc_unmask_irq(struct irq_data *data) { arch_unmask_irq(data->irq); } static struct irq_chip onchip_intc = { .name = "ARC In-core Intc", .irq_mask = arc_mask_irq, .irq_unmask = arc_unmask_irq, }; static int arc_intc_domain_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw) { if (irq == TIMER0_IRQ) irq_set_chip_and_handler(irq, &onchip_intc, handle_percpu_irq); else irq_set_chip_and_handler(irq, &onchip_intc, handle_level_irq); return 0; } static const struct irq_domain_ops arc_intc_domain_ops = { .xlate = irq_domain_xlate_onecell, .map = arc_intc_domain_map, }; static struct irq_domain *root_domain; static int __init init_onchip_IRQ(struct device_node *intc, struct device_node *parent) { if (parent) panic("DeviceTree incore intc not a root irq controller\n"); root_domain = irq_domain_add_legacy(intc, NR_CPU_IRQS, 0, 0, &arc_intc_domain_ops, NULL); if (!root_domain) panic("root irq domain not avail\n"); /* with this we don't need to export root_domain */ irq_set_default_host(root_domain); return 0; } IRQCHIP_DECLARE(arc_intc, "snps,arc700-intc", init_onchip_IRQ); /* * Late Interrupt system init called from start_kernel for Boot CPU only * * Since slab must already be initialized, platforms can start doing any * needed request_irq( )s */ void __init init_IRQ(void) { /* Any external intc can be setup here */ if (machine_desc->init_irq) machine_desc->init_irq(); /* process the entire interrupt tree in one go */ irqchip_init(); #ifdef CONFIG_SMP /* Master CPU can initialize it's side of IPI */ if (machine_desc->init_smp) machine_desc->init_smp(smp_processor_id()); #endif } /* * "C" Entry point for any ARC ISR, called from low level vector handler * @irq is the vector number read from ICAUSE reg of on-chip intc */ void arch_do_IRQ(unsigned int irq, struct pt_regs *regs) { struct pt_regs *old_regs = set_irq_regs(regs); irq_enter(); generic_handle_irq(irq); irq_exit(); set_irq_regs(old_regs); } int __init get_hw_config_num_irq(void) { uint32_t val = read_aux_reg(ARC_REG_VECBASE_BCR); switch (val & 0x03) { case 0: return 16; case 1: return 32; case 2: return 8; default: return 0; } return 0; } /* * arch_local_irq_enable - Enable interrupts. * * 1. Explicitly called to re-enable interrupts * 2. Implicitly called from spin_unlock_irq, write_unlock_irq etc * which maybe in hard ISR itself * * Semantics of this function change depending on where it is called from: * * -If called from hard-ISR, it must not invert interrupt priorities * e.g. suppose TIMER is high priority (Level 2) IRQ * Time hard-ISR, timer_interrupt( ) calls spin_unlock_irq several times. * Here local_irq_enable( ) shd not re-enable lower priority interrupts * -If called from soft-ISR, it must re-enable all interrupts * soft ISR are low prioity jobs which can be very slow, thus all IRQs * must be enabled while they run. * Now hardware context wise we may still be in L2 ISR (not done rtie) * still we must re-enable both L1 and L2 IRQs * Another twist is prev scenario with flow being * L1 ISR ==> interrupted by L2 ISR ==> L2 soft ISR * here we must not re-enable Ll as prev Ll Interrupt's h/w context will get * over-written (this is deficiency in ARC700 Interrupt mechanism) */ #ifdef CONFIG_ARC_COMPACT_IRQ_LEVELS /* Complex version for 2 IRQ levels */ void arch_local_irq_enable(void) { unsigned long flags; flags = arch_local_save_flags(); /* Allow both L1 and L2 at the onset */ flags |= (STATUS_E1_MASK | STATUS_E2_MASK); /* Called from hard ISR (between irq_enter and irq_exit) */ if (in_irq()) { /* If in L2 ISR, don't re-enable any further IRQs as this can * cause IRQ priorities to get upside down. e.g. it could allow * L1 be taken while in L2 hard ISR which is wrong not only in * theory, it can also cause the dreaded L1-L2-L1 scenario */ if (flags & STATUS_A2_MASK) flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK); /* Even if in L1 ISR, allowe Higher prio L2 IRQs */ else if (flags & STATUS_A1_MASK) flags &= ~(STATUS_E1_MASK); } /* called from soft IRQ, ideally we want to re-enable all levels */ else if (in_softirq()) { /* However if this is case of L1 interrupted by L2, * re-enabling both may cause whaco L1-L2-L1 scenario * because ARC700 allows level 1 to interrupt an active L2 ISR * Thus we disable both * However some code, executing in soft ISR wants some IRQs * to be enabled so we re-enable L2 only * * How do we determine L1 intr by L2 * -A2 is set (means in L2 ISR) * -E1 is set in this ISR's pt_regs->status32 which is * saved copy of status32_l2 when l2 ISR happened */ struct pt_regs *pt = get_irq_regs(); if ((flags & STATUS_A2_MASK) && pt && (pt->status32 & STATUS_A1_MASK)) { /*flags &= ~(STATUS_E1_MASK | STATUS_E2_MASK); */ flags &= ~(STATUS_E1_MASK); } } arch_local_irq_restore(flags); } #else /* ! CONFIG_ARC_COMPACT_IRQ_LEVELS */ /* * Simpler version for only 1 level of interrupt * Here we only Worry about Level 1 Bits */ void arch_local_irq_enable(void) { unsigned long flags; /* * ARC IDE Drivers tries to re-enable interrupts from hard-isr * context which is simply wrong */ if (in_irq()) { WARN_ONCE(1, "IRQ enabled from hard-isr"); return; } flags = arch_local_save_flags(); flags |= (STATUS_E1_MASK | STATUS_E2_MASK); arch_local_irq_restore(flags); } #endif EXPORT_SYMBOL(arch_local_irq_enable);